Irwin Tools 1882792 SPEEDBOR Countersink Wood Drill Bit, 8-Piece Product Description IRWIN Wood Countersinks feature a tapered drill and wide flutes that drill fast, clean pilot holes and ensure a tight fit for screws. They have an adjustable four-cutter counter bore attachment that cuts fast and clears chips quickly for fast, smooth countersinking applications. The counter bore feature attaches flats on shank with two hex screws for a secure fit and can be adjusted for controlled pilot hole depth. IRWIN SPEEDBOR countersink bits fit all standard 1/4" quick-change chucks, including impact drills. From the Manufacturer IRWIN Wood Countersinks feature a tapered drill and wide flutes that drill fast, clean pilot holes, and ensure a tight fit for screws. They have an adjustable four-cutter counterbore attachment that cuts fast and clears chips quickly for fast, smooth countersinking applications. The counterbore feature attaches flats on shank with two hex screws for a secure fit, and can be adjusted for controlled pilot hole depth. IRWIN SPEEDBOR countersink bits fit all standard 1/4" quick-change chucks, including impact drills. Features Tapered drill with widened flutes for drilling fast, clean pilot holes Adjustable four-cutter counter bore cuts and clears chips quicker for fast, smooth countersinking Counter bore attaches to flats on shank with two hex screws for a secure fit and can be adjusted for controlled pilot hole depth 1/4 in quick change shank reduces slipping in standard chucks and is compatible with all 1/4 in quick change chucks, including impact drills USA SHIPPING estimates delivery times and we work to get your item to you as quickly as possible and within those times, but please know it may take slightly longer than the estimate.